The present disclosure relates to an imaging element such as a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor and an electronic apparatus using such an imaging element.
In recent years, application of the semiconductor imaging device to the electronic apparatus used in the field of medicine (endoscope camera, vision chip, biosensor, etc.) is being actively promoted. So, achievement of both further enhancement in the sensitivity and size reduction of the device (microminiaturization of the pixels) is required. However, the progression of microminiaturization of the pixels shortens the exit pupil distance and thus causes the following problem. Specifically, the incident angle of light to the on-chip lens (OCL) in the pixel end area becomes large, which causes increase in the reflectance at the OCL surface and increase in vignetting.
Therefore, generally in the image sensor such as CCD image sensor and CMOS image sensor, the problem is addressed by providing an antireflection film on the surface of the OCL or carrying out correction by shifting the center axis of the lens from the center axis of the photodiode (so-called pupil correction).
Furthermore, recently there has been proposed a technique to enhance the light collection efficiency by employing a structure in which the OCL is formed into a cylindrical shape and plural slits are provided in this cylindrical lens (digital microlens) to thereby change the effective refractive index of the lens depending on the incident angle (refer to Japanese Patent Laid-Open No. 2009-266900 (hereinafter, Patent Document 1)).